Eyeglasses, or spectacles, are often worn to refractively correct the wearer's vision, or to protect the wearer's eyes against physical hazards or damaging radiation (e.g., bright or ultraviolet light). Sometimes, eyeglasses are worn simply for aesthetic purposes. As common and fundamental as eyeglasses are, traditional eyeglasses have not changed much in hundreds of years.
Eyeglasses are usually rather heavy, with frames and components made of metal. For example, a pair of frameless (specifically, rimless) traditional eyeglasses 110 is depicted in FIG. 1. As shown, the traditional eyeglasses 110 have two temple bars 112 and 114, each connected to one of two lenses 116 and 118 through hinges 120 and 122, respectively. The two lenses 116 and 118 are connected to each other through a nose bridge 124.
The temple bars 112 and 114, the hinges 120 and 122, and the nose bridge 124 are often made from metal, though some traditional eyeglasses (especially those with plastic frames around the lenses) use metal-reinforced plastics for some of those components.
The metal pieces are relatively heavy, and a significant amount of pressure is exerted on the wearer's nose (through a pair of nose pads 126) and ears (through the temple bars 112 and 114). Moreover, many metals (including, for example, aluminum) are somewhat reactive and tend to corrode in the presence of normal skin secretions—this may also irritate the wearer's skin. Accordingly, the metal components in many traditional eyeglasses 110 are often coated with a less reactive polymer.
This construction is relatively complex and expensive. The metals used in eyeglass components tend not to be relatively inexpensive commodity materials such as aluminum (light but brittle and reactive) or stainless steel (heavier but less reactive), but rather special flexible metal materials engineered to have better performance with respect to bending. Specifically, shape memory alloys have been developed that tend to spring back into their original shape after having been bent. These alloys (such as FLEXON® from Marchon Eyewear, TITANFLEX® from Eschenbach Optik, and others) have improved flexibility characteristics in comparison to other metals, but share some of the same limitations, especially weight and expense. These materials are particularly difficult to work with in manufacturing.
Traditional eyeglass construction also has some limitations deriving from their physical configuration, regardless of materials. The temple bars are subject to bending and breakage because of the lengthy shape. The temple bars place a significant amount of stress on the hinges, which may also be subject to breakage. In turn, the hinges may cause the temple bars to press against the wearer's head, causing some discomfort. This is true to some extent even with modern spring hinges, which are capable of bending past the usual 90-degree limit.
Traditional eyeglasses are not especially compact, and are subject to increased risk of breakage when stored. Generally, for storage, the temple bars 112 and 114 are folded (via the hinges 120 and 122) across the rear of the lenses 116 and 118. Although storage cases are often provided, many eyeglass wearers simply drop their glasses into a purse, bag, or pocket. Even when great care is taken, maintenance and repair is often needed—screws in the hinges 120 and 122 often work their way out over the course of time, and are frequently lost. When such screws are lost, either of the temple bars 112 and 114 may detach from the eyeglasses 110, preventing the eyeglasses from being worn until the screws are replaced.
Small children are also often attracted to eyeglasses, and often grab and handle glasses worn by a caregiver or found within reach. This is another common source of breakage.
Folding glasses have been made that incorporate additional hinges into the temple bars and the nose bridge. Because of the additional hinges, these folding glasses are often heavier, more expensive, and less stylish than traditional eyeglasses.
The mechanical components in traditional eyeglasses also complicate the matter of fitting the glasses to each wearer. Generally, the temple bars 112 and 114 are bent and configured to fit the wearer's head, and distal ear pieces 128 and 130 are also adjusted to permit the glasses to maintain a desired position on the wearer's head with minimal slippage. These adjustments are complex and best performed by trained and licensed opticians. If a pair of traditional eyeglasses is bent or otherwise damaged, which can be a relatively frequent occurrence, the eyeglasses may remain uncomfortable (or at worst, unwearable) until an optician is able to repair and readjust them.
With traditional eyeglasses having borne the same general configuration for nearly three hundred years, and marginal improvements having been made to some materials and components, clearly there is a need for an improved eyeglass design that improves upon and eliminates many of the aforementioned limitations. Such improved eyeglasses would be of lighter weight, relatively inexpensive, non-reactive to the wearer's skin, and resistant to breakage or falling out of adjustment. And preferably, such eyeglasses would be stylish and desirable to those who wear glasses for primarily (or even secondarily) aesthetic purposes.